-LRB- CNN -RRB- -- North Korea resumed firing near its sea border with South Korea on Thursday , South Korean media said , citing Seoul officials .

Artillery shells were fired toward South Korean-controlled Yeonpyeong Island , Yonhap News Agency quoted the officials as saying , adding that the shells fell in waters north of the Northern Limit Line -LRB- NLL -RRB- , the de facto inter-Korean maritime border .

The North fired artillery shells on Wednesday in the same area , saying they were part of an annual training drill .

`` We have confirmed North Korea 's firing of several artillery shells , but they did not cross '' the two countries ' maritime border , said Park Sung-woo , of Seoul 's joint chiefs of staff , according to Yonhap . `` We are on high military alert . ''

`` Following the firing by North Korea , South Korea responded by shooting vulcan canons into the air , a statement that it would not be intimidated by saber-rattling by the communist neighbor , '' Yonhap said .

There were no reports of casualties .

Also Thursday , a South Korean Unification Ministry spokesman said that despite the tension , talks slated for Monday with North Korea would still go forward in the North Korean border town of Kaesong , Yonhap reported .

Seventeen South Korean officials are expected to attend those talks , Yonhap cited Chun Hae-sung , the official , as saying .

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NEW : Talks still on for Monday in North Korean border town , South Korean official says

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North says firing of artillery shells is part of an annual training drill

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Inter-Korean talks still set for Monday , Yonhap cites S. Korean official as saying